L-glutamic acid is a representative amino acid produced by fermentation. L-glutamic acid has a distinctive taste and is thus used broadly not only in the food industry, but also in the fields of medicine, animal feed, and the like.
L-glutamic acid can be produced using L-glutamic acid producing microorganisms. Examples of conventional methods for producing L-glutamic acid include a method of using glutamic acid producing bacteria of so-called coryneform belonging to the genera of Brevibacterium, Corynebacterium, Microbacterium, and variants thereof (“Amino Acid Fermentation”, Gakkai Shuppan Center, pp. 195-215, 1986); a method of using microorganisms belonging to Bacillus, Streptomyces, Penicillium genera, and the like (U.S. Pat. No. 3,220,929); a method of using microorganisms belonging to Pseudomonas, Arthrobacter, Serratia, Candida genera, and the like (U.S. Pat. No. 3,563,857); a method of using Aerobacter aerogenes (now referred to as Enterobacter aerogenes) (Japanese Patent No. 32-9393 (1957)); and a method of using variant strains of Echerichia coli (Japanese Laid-Open Publication No. 5-244970 (1993)), and the like.
As known in the art, conventional methods for producing L-glutamic acid using microorganisms including the aforementioned methods generally include fermentation using microorganisms; accumulating L-glutamic acid in the fermentation liquor in a high concentration; purifying the fermentation liquor to provide L-glutamic acid with high purity; and crystallizing the obtained L-glutamic acid.
Such methods in the art require purification and crystallization of L-glutamic acid. This means that significantly many chemicals are used to carry out these processes, which is not compatible with recent consumer demand for health foods.
To resolve these problems, studies have focused on methods for producing L-glutamic acid without purifying or crystallizing fermentation liquors containing L-glutamic acid. For instance, there has been an attempt to obtain a flavoring using food grade chemicals to be utilized in fermentation of L-glutamic acid without conducting any purification and crystallization and drying the fermentation liquor, from which only microorganism sludge is removed (International Publication No. WO 2009/040150). Such an attempt is to provide a flavoring derived from natural foods having enhanced taste while reflecting the recent preferences by means of excluding the use of industrial chemicals and only using raw materials derived from natural foods.
However, the method disclosed in WO 2009/040150 uses pH modifiers and ammonia as a nitrogen source in the same manner as in conventional fermentation, and does not allow efficient drying of fermentation liquors, thereby making it difficult to adopt the method. Accordingly, there is a need for a process for easily drying fermentation liquors containing L-glutamic acid.
Examples of conventional methods for producing L-glutamic acid are disclosed in Korean Patent Nos. 10-0513996 and 10-0824457, Korean Patent Publication No. 10-2010-0017581A, and the like. All of these methods are aimed at mass production of L-glutamic acid, such as methods for producing L-glutamic acid using genetically engineered L-glutamic acid producing microorganisms, methods for producing L-glutamic acid through continuous fermentation processes, and the like. However, there has been no disclosure regarding a method for producing L-glutamic acid without conducting any purification and/or crystallization steps requiring enormous chemicals by facilitating drying of fermentation liquor containing L-glutamic acid.